Compressor regulator



. June 24, 1941. L. COLLINS 2,246,913

- COMPRESSOR REGULATOR Filed July 7, 19:59 :5 Sheets-Sheet 1 UNLOADING A5 RECEIVER PRESSURE RISES 4 796 5 7 4 3RD 4m.

LoAoma A5 RECEIVER PRESSURE Fms INVENTOR Les/er L. Col/ms.

ATTORNEY e 24, 1941'. L. L. COLLINS 6,913

COMPRESSOR REGULATOR Filed July '7, 1959 3 Sheets-Sheet s INVENTO-R ZeS/er A. Co/bha ATTORNEY Patented June 24, 1941 UNITED STATES PATENT OFFICE COMPRESSOR REGULATOR Lester L. Collins, Franklin, Pa., assignor to Chi-.- cago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Application July 7, 1939, Serial No. 283,289

12 Claims.

This invention relates to regulating apparatus for an air or gas compressor, particularly of the type which is equipped with unloading elements loading elements simultaneously or in the wrong sequence; to permit quick and convenient adjustment ofthe range of the receiver pressure; and the provision of a regulator which is relatively simple in construction, low in manufacturing cost, and capable of operating over long periods without servicing.

In accordance with a feature of the present invention, the unloader, which controls the individual unloader elements, is supplied with fluid under transformed pressure which is related to, but varies to a much greater degree than, the receiver pressure. It is possible, therefore, to select a very narrow pressure range for the receiver while retaining the benefits of a broader range of pressure of the fluid that actuates the unloader.

In accordance with another feature of the invention, the secondary or transformed pressure is arranged to be varied inversely with the pri mary or receiver pressure. This expedient simplifies the design and arrangement of the unloader parts and further increases the sensitivity of the unloader by reducing the pressure acting on one'face of the disc valve while the pressure increases on the opposing face. 7

Another feature is a novel pressure transformer designed to deliver fluid to the unloader under a pressure which has a wider range than the primary OI receiver pressure.

Other objects and features of the invention will appear more clearly from the following descrip: tion taken in connection with the accompanying drawings and appended claims.

In the accompanying drawings which illustrate one embodiment of the invention:

Fig. l is a plan view illustrating a fragmentary portion of a conventional compressor in association with an unloader and transformer designed and arranged in accordance with this invention;

Fig. 2 is a side elevational View of the transformer, unloader and pipes connecting these parts with each other and with the tank or receiver; 7

Fig. '3 is aside view, partly in elevation and partly in section, of the unloader:

. Fig. 4 is a longitudinal sectional view of'the transformer as indicated by the arrows 4 in Fig.1;

Fig. 5 is an enlarged view, chiefly in longitudinal section, of certain parts of the transformer, including the valve mechanism that controls the size of thepassageway throughwhich the pressure fluid flows; Y Fig. 6 illustrates the unloader and an inlet valve unloading element in longitudinal sections, as indicated by the arrows 6A and 63 respectively in Fig. 1, together with the'connecting pipe; and

Fig. 7 is 'a chart showing the relationship be tween the receiver pressure and the secondary or transformer pressure.

For convenience, Figs. 1 and 2 are illustrated on a smaller scale than Fig. 3; Figs. 4 and 6 on a larger scale than Fig. 3; andFig. 5 on a still larger scale.

The unloader U, shown in Fig. 1, is of U0 and UD, arranged to deliver compressed air to pipes H, l2, l3 and H in the order named to reduce the compressor load to /1, /a /4 andno load, respectively. These pipes may be connected to any suitable unloading device. By way of example, they are illustrated as connected to the inlet valve unloading mechanism mounted in the cylinder l5 of a two-stage compressor C, it being understood that the invention is'equally applicable to single stage compressors.

- The compressor C and unloading mechanism, illustrated in Fig. 1, are of the type which operate in accordance with a clearance and by-passing method'of taking ofi and putting on the'load in successive steps. 'In the first two steps, the

load is varied by placing clearance chambers in continuous communication with the cylinders, thus reducing the volume of the intake 'by the expansion of previously compressed air from the end of'the cylinder and clearance pocket 2| to the five .step type and comprises four sections UA, UB,

The unloading element I6 is shown on a larger scale in Fig. 6. This element or device is associated with the inner and outer walls 22, 23 of the compressor cylinder IS, the innerhwall having a stepped opening 24 therethrough in which an inlet valve assembly 25 of conventional plate type is mounted and retained in place by the usual holding members 26. chamber 21 for the insertion and removal of valve assembly 25, an opening 28 is provided "in the outer cylinder-wall 23. The valve lifter 29 is mounted upon valve assembly to engage the plate valves 30 of the'latter' and to hold them open when the compressor cylinder is partially or entirely unloaded. The control apparatus by which valve lifter 29 may be actuated is supported over and may form a part of", or be supported by, the member which seals the opening'28 in the outer Wall 23 of the compressor cylinder. closure comprises a member -32 secured over opening 28 in'an'y suitable manner as by a series of stud' bolts 33.

Member 32" supports a cylindrical bracket 35 which receives alifter actuating piston 36 with a sliding fit. Screws 3'! secure bracket 35 to closure plate 32 and clamp therebetween the outer 'edges'of a diaphragm'38. The diaphragm may consist of any suitable material such as a layer of rubber interposed between two layers of leather. The diaphragm forms one wall ofa variable volume chamber 39 into which the pipe discharges pressure fluid. The valve lifter 29 has an' extension 49' projecting into the inner end of bracket 35 and securedtoa rod 4|, the outer end of which abuts against piston 36. The valve lifter 29 is yieldingly urgedtoward its outermost position, as illustrated, in which a-shoulder on the lifter engages the .inner'end of the bracket 35. The yieldable means comprises a spring 42 interposed between the bracketand an abutment washer 43 on the rod.

It will be apparent to those skilled in the art that when the pipe H delivers fluid under considerable'pressure tothe chamber 39, the pressure on the outer face of the diaphragm will overcome spring 42 and move the'pisto'n 36, rod 4|, and valve lifter 29'inwardly. Fingers 45 on the valve lifter then engage the inletvalves 30 forcing them ofi their seats against the pressure of volute springs 46 and establishing communication between the interior of cylinder I5 and the valve chamber 21 and clearance pocket 20. The valves 30are held'off their seats during both strokes of the compressor'piston (not shown) as long as the pressure in. chamber 39 is maintained. Unloader devices |T|',,|8 and I9 donot require detailed description as they are similar in construction to device l6, although the inlet valves on which devices I8 and I9 operate may connect the interior of the cylinder with atmosphere independently'of any clearance pockets.

The unloader, U which controls the supply of compressed air tothe pipes H, [2,13 and M is illustrated most clearly in Fig. 3 and on the left The To give access to valve side of Fig. 6. It comprises an elongated base 49 at the bottom of which extends a longitudinal bore 50. One end ofthe bore is threaded to receive a pipe 5| from the receiver R while the other end is closed. Four uniformly spaced bores 52 extend upward from the inlet passage to counterbores 53 opening at the upper surface of thebase49. Between the boreland the counterbore is an upwardly facing annular valve seat 54. The four counterbores are associated with v unloader sections UA, UB, U0 and UD, respectively. Each counterbore receives a body member 55011 the associated section with a snug fit.

, Spacer elements such as shims 56 are interposed betweenthe upper face of the base 49 and an annular shoulder on the body member 55. Any desired means, such as vertical bolts 5! and horizontal. bolts 58, may be employed for securing thebocly member relative to the base 49.

' The lower end of the body 55 terminates in an annular valve seat} 66 somewhat larger in diameter than the lower seat 54 and is axially spaceditherefrom.; counterbore 53 provides a valve chamber 6| which is divided into upper and lower compartments by a disc or plate valve 62. Valve 62 is formed with a reduced edge making a line contactwith the wall of valve chamber 6| thus minimizing frictional resistance to its movement. Valve 62 is'ncrmally held in engagement with loweriseat 54 to :cut off the fluid supply from inlet bore '52. The holding means include a spring 64 disposed in body 55, the spring acting on the valve through a plunger 65 having a head 65a engaging the valve 'and provided with an abutment collar 6% for the spring. At its opposite end spring 64 engages the wall 66 forming an integral part of the body 55.

The lower part of the valve chamber 6| which surrounds the valve seat54-is' connected through bore6'! to a tapped opening 68 to which may be attached one of the pipes II, I 2, H or M leading to-thecompressor C. Y A check valvecomprising a spring-pressed ball 69 -may be interposed between thebore .61 and the outlet 63. The upper part of the valve chamber 6|, which surrounds the upper. seat is connectedto the outlet opening 68 byway of a passage 69. It is alsoconnected to a tapped opening 19 to which may be attached a pressure gauge or indicator 1|.

When theunloader section UA is in the load condition, the receiver pressure acts against the lower face of the disc valve 62 over an area circumscribed by the annular seat 54 in opposition to the pressure of the spring 64 and supplemental holding means which will be described presently. Priorto the unloading-operation the parts are in the position shown in Figs. 3 and 6 with the valve 62 held against its lower seat 54 and both the outlet pipe H and indicator opening 16 out 01f from communication with the receiver pressure passage 5!]. When the receiver pressure rises above a predetermined amount, it overcomes the opposing spring and supplemental pressure to trip the valve 62 to its upper seat 60. The air pressure on the bottom of the disc acts over a greater area while the valve is'in the upper position than when the valve engages the lower seat 54, the arrangement being such that the valvetends to remain in a stable condition according to its previous adjustment until there is a substantial change in pressure causing the valve to move. when the valve moves to upper seat 6!! it connects the receiver pressure passage 50 through bore 52, around lower seat 54, through bore 61, past check valve 69 and through outlet bore 68 to the pipe I'I leading to unloader'device I6. Opening III associated with recess 6|, admits air simultaneously to the gauge H which indicates that the compressor is in at least the first stage of unloading. Ball check valve 99 prevents fluttering of the disc valve 62 in a manner described more fully in Moody and Hoffman Patent 1,682,848, granted September 4, 1928. Further increase in receiver pressure trips the disc valves associated with unloader sections UB, U and UD'in the order named to effect /2, andcomplete unloading, respectively, as herein-before described.

An important feature of the present invention resides in the provision of means for. varying the pressure on top of the disc valve 62, as Well as on the bottom, in response to pressure variations in receiver R. Accordingly, a diaphragm I5 is clamped between the upper face of the unloader section body 55 anda cover I6 forming a pressure chamber 11 above the diaphragm. The lower face of the diaphragm seats on a collar I8 at the upper end of rod 65, whereby'the diaphragm pressure supplements that of spring 64 and opposes receiver pressure at the bottom of the disc valve 62. A pipe I9, leading from the transformer T, delivers transformed pressure fluid through branches 19a, 191), I90 and 19d to the pressure chambers 'I'I in the unloader sections UA, UB, UC and UD, respectively. The transformer is so arranged that as the pressure in receiver R and on the bottom faces of disc valves 62 rises, the pressure in chambers 11 decreases, preferably to a greater degree.

The transformer T, which delivers transformer pressure fluid to pipe i9, is supplied with fluid; under receiver tank pressure by a pipe 8|. It comprises lower and upper casing sections 83 and 84 respectively, a gasket 85 between said-sections, and bolts (not shown) for securing the sections together. The sections are recessed to provide a middle chamber 86 for reception of pressure fluid. The middle chamber is continuously vented through an outlet 8'! under control of an adjustable needle valve 88. Chamber 86 is also continuously in communication through port 89 with outlet pipe I9 leading to unloader U. Compressed air is delivered to the middle cham ber 86 from receiver R, pipe BI, inlet port 9I, lower chamber 92 and central bore 93, the passage between the lower chamber and central bore being controlled by valve mechanism responsive to an increase in receiver pressure to reduce the rate of flow to the middle chamber 86 and vice versa.

The valve mechanism, as shown in Figs. 4 and 5, includes a valve cylinder 95, the upper end of which has a projection 96 seated in the central bore 93 and the lower end of which is seated in a recess 91 in aplug 98. 'A gasket 99 prevents leakage of pressure fluid from lower chamber 92 around the projection 96 to the middle chamber 86. Passage of pressure fluid from the lower to the middle chamber takes place through filter I9I, ports .192 to the interior of the valve cylinder, through a passageway between a valve plunger I93 and a valve seat I94, and through a central opening I95 in the upper end of valve cylinder 95. Plunger I93 may be provided with circumferential grooves to receive lubricant and reduce the rubbing surface; and with a vertical groove (not shownl to equalize the pressure on the top and bottom of the plunger. A compression spring I96 tends to hold plunger I93 on, or near, the seat I04.

It is opposed by pressure responsive means acting against a pin I93a carried by the plunger I93 and extending into the middle chamber 86.

The pressure responsive plunger actuating means comprise a diaphragm I91 secured at its periphery between the upper casing section 84 and a hood I08 bolted to the casing. The hood encloses a pressure plate I09 seated on the diaphragm, a compression spring H9 engaging said plate, a spring button III at the upper end of the spring and a screw H2 for adjusting the tension of the spring. A look nut H3 holds the screw in adjusted position. A push rod II I, bolted at its upper end to the pressure plate I09, extends downward into middle chamber 86 and abuts against the pin I93a on plunger I93. The push rod moves vertically in unison with 'the central part of the diaphragm I91 in response to pressure fluctuations at the bottom of the diaphragm.

The upper section 84 has a central opening providing an upper chamber H6 between the walls of the opening and a concentrically arranged bellows II'I surrounding push rod IN. The upper end of the bellows is secured to the central portion of the diaphragm IIl'I. The lower end at its periphery is clamped between the section 84 and a closure plate I I8 to seal the upper chamber IIB, which surrounds the bellows, from the middle chamber 86 below and within the bellows. The upper chamber communicates, through passage H9, with pipe I20 supplying compressed air from receiver R.

Let it be assumed that the compressor C is operating under full load with the admission or rate of flow from the receiver R substantially balancing the supply by the compressor. Compression spring H0 in transformer T pushes down on diaphragm I01 and rod II to hold valve plunger I93 in spaced relation from valve seat I94 thereby admitting receiver pressure from lower chamber 92 to the middle chamber 86, which in turn is connected through pipe I9 to the chamber 11 in each of the sections in the unloader U. Receiver pressure in the upper chamber H5 of the transformer: opposes spring IIIJ but is insufiicient at this time to prevent the spring from holding the plunger I93 away from valve seat I94. Thepressure fluid passing from lower chamber 92 to middle chamber 86 is balanced by air escaping through vent 81, and the parts remain'in a state of equilibrium. In the unloader U, all disc valves 52 are held against their lower seats 54 in the load position by the spring 55 since the transformed pressure on top of the diaphragm l5 and the receiver pressure on the bottom of disc 52 almost balance each other.

Assume now that the demand on the receiver R diminishes, causing the pressure therein to rise gradually. I Transformer spring H0 meets with increasing opposition by receiver pressure in upper chamber H6 permitting Valve plunger I93, under the influence of spring I95, to ap-' proach more closely to the valve seat I94 and increasing the resistance to the flow of compressed air. from the lower chamber 92 to the middle chamber 85. The resistance of the vent 81 being unchanged, the pressure in the middle chamber must drop causing a corresponding drop in the pressure on all of the unloader diaphragrns I5. With the downwardly acting transformer pressure decreasing and the upwardly acting receiver pressure increasing, a point of equilibrium is passed and the disc valve 62 in unloader section UA is tripped to its upper or unload position. In this position, receiver air is admitted to pipe I! to actuate the first, unloader device 16. If the receiver pressure continues to rise, the remaining unloader sections UB, UC and UD operate in the order mentioned to effect /2, and complete unloading, respectively.

The pressures at which the respective disc valves trip are controlled by adjusting the springs 64 at different tensions. The spring tension may be regulated by the selection of shims H8 of desired thickness, between the spring 64 and collar 65b. Tightening the spring raises the required receiver pressure to operate the disc valve; loosening it lowers the required pressure. The lift of the valve 62 may be regulated by the shims 56. i Selection of receiver pressure is ordinarilyeffected by adjusting the screw H2 that abuts against the spring H in the transformer. Tightening the spring raises the receiver pressure, while loosening the spring lowers it. Operation of the unloader may be controlled by the vent needle valve 88 in the transformer. Closing the vent tends to retard operation of the unloader, while raising it tends to speed up the operation.

Referring to Fig. 7, it is seen that a slight variation in receiver pressure is accompanied by a large variation in transformer pressure. Among the advantages of using transformed pressure or a combination of receiver and transformed pressure, instead of receiver pressure alone, to actuate the disc valves, are that the unloader sections may be regulated to respond to the selected receiver pressures with a greater degree of accuracy and dependability, and that the unloader valves are assured of operation one at a time in the proper sequence.

In returning from the fully unloaded to the fully loaded condition, the unloader U operates step-by-step in the reverse order. As indicated in Fig. 7, the amount of receiver pressure necessary to trip an unloader section to unload position is considerably higher than the pressure at which the section is restored toloading condition. This is due to the arrangement of the differential pressure areas on the disc valve 62.

The bellows Ill, and the parts to which it is attached, are so constructed that the bellows may be conveniently removed and replaced by another of different diameter. To obtain a close range of receiver pressure a bellows of relatively small diameter is employed; and a wider range is obtainable by the use of a larger bellows. According to an important feature of the invention, the lower part of diaphragm I0! is exposed to the pressure of upper chamber I I6 outside of the bellows and middle chamber 86 within the bellows. As pointed out hereinbefore, the pressure in chamber 86 rises while the pressure in chamber H6 falls and vice versa. Increasing the diameter of the bellows transfers a part of the area at the bottom of the diaphragm from chamber I I6 to chamber 86 and thus affects the range of receiver pressure.

What is claimed is:

1, In a pump or compressor having a receiver, a cylinder and a plurality of unloading devices arranged to effect step-by-step unloading of the compressor, automatic regulating means for said devices comprising an unloader having a series of pressure responsive valves controlling admission of pressure fluid to said unloading devices and having a series of pressure chambers controlling the operation of the valves, and a pressure transformer interposed between the receiver and the unloader pressure chambers to vary the pressure of the latter inversely with the receiver pressure.

2. In a compressor having a receiver, a cylinder and a plurality of unloading devices associated with the cylinder, an unloader for controlling the operation of the unloading devices,

said unloader having a series of valves associated with the respective unloading devices, each valve being movable between two seats with a snap action, passages arranged to deliver fluid to the associated unloading device when the valve is in one position only, fluid pressure means corresponding to receiver pressureacting on the valve and tending to move it toward unload position, and opposed fluid pressure means tending to hold the valve in load position.

3. A compressor unloader comprising axially spaced upper and lower valve seats, the upper seat being of larger diameter than the lower, a disc valve movable between said seats with a snap action, a passageway arranged to be opened when the valve moves to its upper seat to deliver pressure fluid to an unloading device, means exposing the lower face of the valve to receiver pressure, a plunger acting on the upper face of the valve, a spring moving said plunger and valve downward, and means supplementing the action of the spring. the last-named means comprising a diaphragm connected to said plunger and a fluid pressure chamber above said diaphragm. 7 p

4. A compressor unloader according to claim 3 which includes means for varying the pressure in the diaphragm chamber inversely with the receiver pressure,'whereby the downward pressure on the valve decreases and the upward pressure increases as the receiver pressure rises and vice versa.

5. In a fluid compressor regulator, a pressure transformer comprising a casing. having an inlet port arranged to be connected to a pressure fluid receiver, an outlet port arranged to be connected to an unloader, a chamber in said casing in continuous and substantially unrestricted communication with the outlet port, a relatively restricted vent passage from said chamber, a passageway between said inlet port and said chamber, and

automatic means responsive to receiver pressure for adjusting the size of said passageway and consequently the pressure in said chamber.

6. In a fluid compressor regulator, a pressure transformer comprising a casing providing a primary and a secondary chamber, means arranged to place said chambers in substantially unrestricted communication with a source 'of pressure fluid and an unloader respectively, a vent arranged to effect slow but continuous leakage of pressure fluid from said secondary chamber, a passageway between the primary and'secondary chambers, a valve controlling the size of said passageway and consequently the pressure in the secondary chamber, said casing having a third chamber arranged to be supplied with fluid under pressure corresponding to receiver pressure, one wall of said third chamber being movable in response to pressure therein, and means connecting the movable wall with the valve to control the size of the passageway in response to receiver pressure.

7. In a fluid compressor regulator, a pressure transformer comprising a casing providing a primary and a secondary chamber, means arranged to place said chambers in substantially unrestricted communication with a source of pressure fluid and an unloader respectively, a vent arranged to effect slow but continuous leakage of pressure fluid from said secondary chamber, a passageway between the primary and secondary chambers, a valve controlling the size of said passageway and consequently the pressure in the secondary chamber, said casing having a third chamber arranged to be supplied with fluid under pressure corresponding to receiver pressure, yieldable means moving the valve toward open position and fluid actuating means for the valve proportional to the pressure in the third chamber and opposing the yieldable means, whereby the secondary pressure varies inversely with the receiver pressure.

8. In a fluid compressor regulator, a pressure transformer comprising a casing providing a primary and a secondary chamber, means arranged to place said chambers in substantially unrestricted communication with a source of pressure fluid and an unloader respectively, a vent arranged to eiTect slow but continuous leakage of pressure fluid from said secondary chamber, a passageway between the primary and secondary chambers, a valve controlling the size of said passageway and consequently the pressure in the secondary chamber, said casing having a third chamber arranged to be supplied with fluid under pressure corresponding to receiver pressure, one wall of the third chamber being defined by a diaphragm, a spring acting on said diaphragm in a 1 direction tending to reduce the size of the third chamber, and a push rod connecting the central part of the diaphragm with the control valve to regulate the position of the valve and the size of the passageway.

9. In a fluid compressor regulator, a pressure transformer according to claim 8 in which the diaphragm is on the side of the third chamber remote from the control valve and in which the push rod is surrounded by a bellows defining the inner wall of the third chamber.

10. In a pump or compressor having a receiver, a cylinder and a plurality of unloading devices arranged to effect step-by-step unloading of the compressor, automatic regulating means for said devices comprising an unloader having a series of pressure responsive valves controlling admission of pressure fluid to said unloading devices and having a series of pressure chambers controlling the operation of the valves, and means for transmitting pressures from said receiver to said pressure chambers including a pressure transformer effecting wide pressure changes in said chambers in response to relatively small pressure changes in said receiver.

11. In a pump or compressor having a receiver, a cylinder and an unloading element associated with the cylinder, means for directing pressure fluid to said unloading element to operate said element, a valve movable to open and closed positions to control the flow of pressure fluid to said unloading element and adapted to prevent the flow of pressure fluid to said element when in closed position, spring means pressing said valve toward closed position, auxiliary means pressing said valve toward closed position, and means for increasing and reducing the pressure of said auxiliary means in a predetermined relation to the rise and fall of receiver pressure.

12. In a pump or compressor having a receiver, a cylinder and an unloading element associated with the cylinder, means for directing pressure fluid to said unloading element to operate said element, a valve movable to open and closed positions to control the flow of pressure fluid to said unloading element and adapted to prevent the flow of pressure fluid to said element when in closed position, a pressure chamber communicating with said receiver, means movable in response to pressure variations in said pressure chamber for moving said valve to closed position, a vent of reduced diameter connecting said pressure chamber to atmosphere, and means movable in response to pressure variations in said receiver for restricting the passage of pressure fluid from said receiver to said pressure chamber, said means acting to reduce the rate of flow to said chamber as the receiver pressure increases and to allow an increased flow as the receiver pressure drops.

LESTER L. COLLINS. 

